How to Extract Multiple Parameters from a String in Java or Scala

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How to Extract Multiple Parameters from a String in Java or Scala

Dealing with strings that contain multiple parameters, particularly in URLs, can be challenging. Imagine you have a string that looks like this:

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From this string, you need to extract three specific parameters:

taxYear: a 4-digit year (e.g., "2021")

startMonth: a 1 or 2-digit month (1 to 12)

endMonth: a 1 or 2-digit month (1 to 12)

If you’ve tried to isolate parts of the string using simple substring methods but found it unreliable and not flexible (for example, changing the month value, but your code still returns the old one), you’re not alone! Fortunately, there is a more systematic way to extract these parameters effectively.

Step 1: Split the String

First, you need to split the string using the question mark ? to separate the main URL from the parameters.

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Step 2: Further Split the Parameters

Next, you’ll take the second part of the split (which contains your parameters) and split it again using the & character.

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Step 3: Store the Parameters in a Map

To easily access the parameters by name, store the key-value pairs in a HashMap:

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Step 4: Extract Values into Variables

Finally, you can retrieve the values from your map and convert them to the appropriate data types:

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Complete Code Example

Here’s the complete code for extracting the parameters from the string:

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Conclusion